Certain emergency circumstances demand immediate intravenous therapy for patients facing life threatening loss of bodily fluids due to accidents or other critical care applications found in emergency centers or in critical care facilities of a hospital. IV therapy requires the infusion of liquid substances directly into a vein of the patient. Typically, IV fluids in a bag suspended from a IV pole employing a drip chamber that is connected to a peripheral IV line which consists of a short catheter inserted through the skin into a peripheral vein outside of the chest or abdomen. This is usually in the form of a cannula-over-needle apparatus, in which a flexible plastic or polymer cannula comes mounted on a metal trocar. Once the tip of the needle and cannula are located properly in the vein, the trocar is withdrawn and discarded. Meanwhile, the cannula is advanced inside the vein to a predetermined position where an external hub or valve area of the catheter is secured to the patient's body by medical tape or the like to hold it in place. Blood is often withdrawn at the time of the initial insertion of the cannula into the patient's vein. This is the most common intravenous access method used in both hospitals and in the field by paramedics or emergency medical technicians (EMTs).
The calibers of cannula generally range from 12 to 26 gauge with 12 being the largest and 26 being the smallest. The part of the catheter remaining outside of the skin is called the IV connecting hub or IV valve that is connected to the IV lines back to the IV bag of fluids. For example, an all-purposes IV cannula for infusions and blood draws might be an 18 and 20 gauge sized cannula manufactured by BD/Becton Dickinson Infusion Therapy AB. This intravenous cannula comes with an inner needle that is removed once the flexible portion of the cannula is fully inserted into the patient's vein.
Due to the different skill levels of the medical personnel inserting the IV cannula into the peripheral vein of a patient's hand or arm, complications sometimes develop in a number of the patients receiving IV fluid therapy from infiltration. This is a condition where through improper insertion or withdrawal of the cannula either into or from a peripheral vein, respectfully, results in IV fluids leaking into the surrounding tissues around the vein causing a potential serious health condition known as infiltration.
Before the blood is withdrawn at the time of insertion, this is also the time to detect whether the cannula portion of the catheter is being properly inserted in the patient's vein or not. If the cannula is not sited properly or the vein is missed or even pierced where the cannula goes through the vein and enters into the surrounding subcutaneous tissue rather than remaining in the vein, complications may develop for the patient receiving the IV fluid therapy. Many serious complications can result from improper cannula insertion into the vein. The potential complications include edema causing tissue damage or may even include necrosis depending on the medication or fluid being infused. This extravasation is a leakage of infused fluids into the vasculature of the subcutaneous tissue surrounding the vein. The leakage of high osmotic solutions or chemotherapy fluids can result in significant tissue destruction or other complications. Therefore, in an emergency room of a hospital where interns or nurses are treating a patient by administering fluids intravenously, it becomes a critical factor in the safety of the patient that IV fluids are indeed flowing into the vein of the patient and not into the surrounding tissue. Insertions of a cannula by EMTs in the field at accident scenes who need to administer IV fluid therapy to an injured party are a critical application where the cannula needs to be inserted properly into the vein and to remain within the vein during transportation to the hospital to prevent a loss of life.
However, due to human error, mistakes are bound to be made while inserting the cannula into a vein or the vein is missed altogether during the initial insertion of the needle/cannula. Other times due to movement of the patient by medical personnel or by the patient themselves, the cannula begins to withdraw from the vein. To avoid this chronic problem or other problems during insertion of the needle through the skin into the vein, the medical staff needs some indication about the successful insertion of the needle and cannula into the patient's peripheral vein. The medical personnel also need a convenient way to monitor and then alerted to any withdrawal of the cannula from the vein during IV fluid treatment.
To solve this problem of cannula tip placement and to reduce the incidents of infiltration of IV fluids into the surrounding tissues instead of the vein, the intern, nurse or EMT tasked with the needle insertion into a patient's vein to start the IV therapy would greatly be helped by knowing that their insertion of the cannula into the peripheral vein is being accomplished successfully by some type of feedback signal indicating that the proper insertion of the cannula tip within the vein of a patient has occurred.
To solve the problem of infiltration after the initially insertion of the cannula into the patient's vein when the cannula tube backs out of the vein or begins to leak for various reasons, a variety of complex leak detectors have been proposed for detecting a leak or an extravasation of a liquid injected through a needle into a blood vessel of a human body, as described, for example, in U.S. Pat. Nos. 7,546,776, 6,408,204, 5,964,703, 5,947,910, 6,375,624, 5,954,668, 5,334,141, 4,647,281, and 4,877,034. Still other U.S. Pat. Nos. 6,408,204, 5,964,703, 5,947,910 disclose complex leak detectors for detecting a leaking liquid due to a change in impedance on the skin surface of a human body; U.S. Pat. Nos. 6,375,624, 5,954,668, 5,334,141, 4,647,281 disclose leak detectors for detecting a leaking liquid from a change in temperature of a human organ; and U.S. Pat. Nos. 8,078,261 and 4,877,034 discloses a light-guided catheter and leak detector for placement through the skin and for detecting a leaking liquid from a change in optical characteristics of the blood, respectively. There are a number of various prior art solutions to the infiltration problem that center around the monitoring of the pressures of the IV fluids administered to the patient. The pressure information is used to control the flow of the IV fluids. Examples of pressure monitoring systems are shown in U.S. Pat. Nos. 4,277,227; 4,457,751; 4,534,756; 4,648,869 and 7,169,107.
However, none of these prior art patents teach a highly reliable portable apparatus and method of guiding a catheter into a vein and then detecting the proper insertion of the IV cannula of the catheter during its insertion into the patient's peripheral vein by providing a feedback signal either visual or audible for the intern, nurse or EMT starting the IV therapy. Moreover, this smart IV catheter is highly portable and capable of being used in emergency situations outside of a doctor's office or hospital setting in field emergency situations by EMTs prior to the patient being taken by ambulance to the hospital's emergency room.
Most of these prior art infusion detection systems referred to above while doing a good job in detecting problems once the IV therapy begins, the prior art systems do not monitor the initial insertion of the IV cannula into the vein to make sure the cannula is properly inserted into the patient's vein. Some of the prior art systems even require a substantial infusion of IV liquids prior to even detecting a leakage such as a leakage that occurs when the cannula pulls out of the patient's vein. In short, all of these systems are rather complicated and therefore require expensive pieces of equipment that are not necessarily readily available to paramedics or EMTs in the field who must start the IV therapy to an injured patient at an accident scene or even immediately available to the nurses, interns or EMTs even in a hospital emergency room setting.